Given current standings, quarter final is 'par' for England. Many coaches have got England that far and not got sacked for failing at that point. IIRC, the only one that got them further than that in recent years resigned afterwards. England do not, in general, hastily sack their manager. Quite a few people would say the FA aren't nearly decisive enough.
In this case however I think it's more the case that there's nobody inside the FA brave enough to actually tell Fabio Capello to his face that he's been fired...
Jon